This invention relates to a coil winding arrangement for an electrical machine that permits greater latitude in the machine operation while maintaining a simple, low cost construction.
There are many instances where different windings or groups of windings are employed in an electrical machine that cooperate with the same magnets to serve different purposes. For example, in rotating electrical generators one group of coil windings may have a rectified output for charging a battery while another group may be employed for operating electrical devices directly. This is common in many vehicle applications such as various two or three wheeled land vehicles. When this is done, some mechanism must be employed for providing the electrical connections between the groups of coils and the device or devices powered.
Generally the windings are formed around the pole teeth of an armature that cooperates with juxtaposed relatively moveable permanent magnets of alternating polarity. These magnets are positioned at the ends or the pole teeth that are spaced from the connecting ring from which the teeth extend in a radial direction. The windings are formed around insulating bobbins that surround the pole teeth. Generally the terminal connections are made to taps supported at the base of the bobbins.
If, as is normal, the coils of each group of windings are around circumferentially adjacent pole teeth and thus the taps for the winding ends may be placed in proximity to the beginning coil and final coil of each group. However, the number of pole teeth or coil windings for each group will vary, depending on the specific application. Thus a special bobbin assembly must be made for each application, thus increasing the piece price.
An alternate solution is shown in U.S. Pat. No. 6,583,529, issued Jun. 24, 2003 and assigned to the assignee hereof. In that case there are provided a plurality of taps and special connectors that may be utilized to change the coil groupings. This is a good solution to the problem, but still has some cost disadvantages since multiple taps and special connectors are required.
It is, therefore a principle object of this invention to provide an improved coil winding arrangement for a rotating electrical machine that permits selective grouping of coil windings with a minimum number of electrical taps for their connection.
In the past and as noted above, the grouping of coil windings has been on separate pole teeth. This somewhat limits the flexibility in selecting the groups and may at times limit the total machine capacity through a reduction in the winding density.
It is therefore another principle object of the invention to provide a winding arrangement that has greater flexibility in winding selection than heretofore available.
A first feature of the invention is adapted to be embodied in a coil winding arrangement for a rotating electrical machine comprising a ring having a plurality of radially extending pole teeth. A first coil winding having individual coils encircles a first number of circumferentially spaced pole teeth. In accordance with this feature of the invention, a second coil winding encircles a second number of circumferentially spaced pole teeth including at least some of the pole teeth encircled by said first coil winding.
A second feature of the invention is adapted to be embodied in a coil winding arrangement for a rotating electrical machine comprising a ring having a plurality of radially extending pole teeth. A first coil winding having individual coils encircles a first number of circumferentially spaced pole teeth. A second coil winding encircles a second number of circumferentially spaced pole teeth. In accordance with this feature of the invention, four taps are formed at the ring portion to which respective ends of said coil windings are electrically connected. Two of these taps are disposed adjacent to two circumferentially adjacent pole teeth each of which is encircled by a respective one of the coil windings. These two taps are electrically connected to a respective end of the coil winding of the adjacent pole teeth. The remaining two of the taps are disposed adjacent to one pole tooth encircled by at least one of the coil windings. Each of these remaining two taps are electrically connected to the other ends of a respective one of the coil windings.